<VV> turbocharger cooling

[jvhroberts at aol.com]

 WHAT cars have the turbos on top of the exhaust manifolds? My 300ZXTT has them hanging from below it's exhaust manifold. Our Subarus have them mounted not unlike a Corvair. (Subarus don't have exhaust manifolds) Most L4 engines have them hanging below their exhaust manifolds. I've yet to see anything remotely modern that's not a truck or a piece of farm or construction equipment with the turbo on top of the manifold. 

It's the heat flowing back from the turbine wheel and the turbine housing after the cooling oil flow has stopped that causes the trouble. 

And these days, why use water, as a once through coolant? Intercoolers, better fans, etc., are a better way to go..





 





 



-----Original Message-----

From: FrankCB <frankcb at aol.com>

To: shortle <shortle556 at earthlink.net>; Frank F Parker <fparker at umich.edu>; jvhroberts <jvhroberts at aol.com>

Cc: virtualvairs at corvair.org

Sent: Mon, 25 May 2009 10:42 pm

Subject: Re: <VV> turbocharger cooling

















Many of the newer cars have their turbochargers sitting directly on top of the exhaust manifold which retains lots of heat on a shutdown.? If their engines?are not idled after a hard run and before shut down, the heat from the exhaust manifold really "cooks" the oil sitting?UNMOVING in the turbo bearing.? So if you don't have water cooling in your turbo, use a fully synthetic oil AND idle the engine a few minutes BEFORE shutdown to keep the oil flowing through the bearing while the heat has a chance to dissipate.? There are even aftermarket devices available that will keep your engine running at idle for a few minutes AFTER you remove the ignition key.




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Since Corvair turbos generally don't sit on top of their exhaust manifolds, they usually have less need for using water cooling on their bearings.




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While Tom K. didn't use water cooling on his turbo bearings, he did use "water cooling" to keep his engines together for his Bonneville runs (156 mph on gasoline and 173 mph on propane).




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Frank "boost substitutes for cu. in." Burkhard




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In a message dated 05/25/09 15:04:31 Eastern Daylight Time, shortle556 at earthlink.net writes:






I worked in a new car dealer (Volvo cars) as a service tech. in the eighties and replaced many a turbocharger (made by Garrett) because the cars were smoking out the tailpipe. We also replaced the oil feed pipe as it was a requirement for warranty reasons. Most of these units were not getting oil to the turbo due to not changing the oil enough or by not letting it idle after driving. Then in 1987 they changed to a water cooled turbo and that pretty much ended the turbo jobs unless the owners never changed the oil. Then in 1989 they started using a Mitsubishi turbo that was also water cooled but had a feed pipe almost twice the size of the Garretts. These turbos seemed to last the life of the car so long as the owners were reasonably conscience of oil change intervals. Of course the water cooled turbos got A GOOD AMOUNT OF COOLANT FLOWING through the center section from the water pump. It was not a siphon effect that would keep it cool but a pressurized flow. All these cars us 

ed EFI and wastegates, and starting in 1985 they all had intercoolers. 

Timothy Shortle in Durango Colorado 







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